1. Field of the Invention
The present invention relates to internal combustion engines and straddle-type vehicles including the internal combustion engines.
2. Description of the Related Art
A conventionally known internal combustion engine (hereinafter referred to as an engine) of a vehicle such as a motorcycle includes a shroud for covering a portion of the engine and a cooling fan for supplying air to inside of the shroud (see JP-A-7-293238 and JP-A-2001-317349, for example). In such an engine, the cooling fan produces a flow of air inside the shroud. Thus, a portion of the engine is cooled by the air. This type of engine is idiomatically referred to as a “forced air-cooled engine”.
JP-A-7-293238 discloses an engine including an air supply fan connected to an end of a crankshaft, and an air supply cover for covering the air supply fan, a cylinder block, a cylinder head and a head cover. In a region of the air supply cover facing the air supply fan, there is formed a suction port through which air is sucked. The air sucked through the suction port is supplied to the whole of the cylinder block, the cylinder head and the head cover.
JP-A-2001-317349 discloses an engine including a cooling fan connected to an end of a crankshaft, and a cooling wind cowling for covering the cooling fan, a cylinder block, and a cylinder head. In a region of the cooling wind cowling facing the cooling fan, there is formed a suction port. Air sucked through the suction port is supplied to the whole of the cylinder block and the cylinder head.